Antioxxdants



' Reiuued Nov. s, 1946 ANTIOXIDANTS Louis H. Howland, Watertown, and Philip '1. Paul, Naugatuck, Conn., assignors to United States Rubber Company, New York, N. Y., a corporation of New Jersey No Drawing. Original No. 2,377,423, dated June 5,

1945, Serial No. 396,580, June 4, 1941. Application for reissue May 23, 1946, Serial No. 671,889

This invention relates to improvements in antioxidants.

An object of the invention is to provide chemicals for retarding the deterioration of organic substanceswhich tend to deteriorate by absorption oxygen from the air, such as rubber or allied gums, artificial rubber-like materials such as neoprene (polychloroprene), and buna (polyoleilnes), unsaturated fatty oils such as unsaturated vegetable oils, essential oi1s,'petroleum oils and their derivatives, such as gasoline, lubricants, soaps, aldehydes, paints, and the like. A further object 01' the invention is to provide chemicals which additionally actto improve the resistance of rubber to cracking when subjected under strain to atmospheric conditions. Further objects will be apparent from the following description.

According to the invention the organic substances have incorporated'therein a product of reaction of a diene and an aromatic amine selected [from a class consisting of primary, andsecondary amines. Theamine may contain more than one amine group and the aromatic nucleus attached to the amine nitrogen atom may contain various substituents. Exemplary of amines that may be reacted with the diene are: aniline, o-toluidine, m-toluidine, p-toluidine, p-chloroaniline, p-bromo aniline, p-allyloxy aniline, p-amino isopropenyl benzene, o-amino ethyl benzenem-amino isopropyl benzene, p-amino tertiary butyl benzene, p-amino diphenyl, o-anisidine, m-anisidine, p-anisidine, p-phenetidine, p-phenoxy aniline, p-amino phenol, alpha naphthylamine, beta naphthylamine, 1,4 naphthalene diamine, diphenylamine, p-methoxy diphenylamine, p-methallyloxy diphenylamine, 2-4 dimethyl aniline, thio p-anisidine. 4-amino diphenylamine, 4-amino 4',.-methyl diphenylamine, 4,4'-diamino diphenyl methane, 3,3'-diamino diphenyl methane. 2,2'-diamino diphenyl methane, p-phenylene diamine, m-phenylene diamine, ophenylene diamine, N,N'-diphenyl p-phenylene diamine, 4-amino N-methyl diphenylamine, 4-.

7 Claims. (Cl. 260-800) 1,3 butadlene, 1,2 diethyl 1,3 butadiene, 1,5 hexadiene, 1,6 heptadiene, 1,4 dimethyl 1,3 butadiene, l-phenyl 1,3 butadiene, 2-phenyl 1,3 butadiene, Z-p-toLyl 1,3 butadiene, l-p-xenyl 1,3 butadiene,

1,4 pentadiene, 1 vinyl, 1,3-butadiene, cyclopentadiene, and cyclohexadiene, etc.

The reaction products of the invention are generally prepared by reacting the diene with the amine at an elevated temperature, preferably in the range from about 100 to about 200 0., in the presence of suitable acidic catalysts, the proportion of the diene in the reaction mix being, as illustrated in Examples l-8, in molecular excess compared to the molecular proportion of the amine. Either organic or inorganic solvents may be used such as acetic acid, alcoho1,.

water, dioxane, acetone, methyl ethyl ketone, etc. As condensing agents, acidic substances such as the following may be used: iodine, bromine, chlorine, hydriodicacid, hydrobromic acid, hydrochloric acid, sulfuric acid, oxalic acid, aluminum chloride, ferrous chloride, hydrofluoric acid, succinic acid, chromic chloride, manganese chloride, acide activated bleaching earths.

The chemicals have special and outstanding properties in connection with the preservationoi rubber and vulcanized rubber goods against I the deterioration by oxygen, heat, or flexing. Al-

though some of the products are crystalline, a great many oi them are either thick syrups or resins having very little odor per se and impartmg substantially no odor to rubber. They are general volatile in sub-atmospheric pressures without decomposition. They are generally very soluble in rubber and may be used in large amounts with substantially no danger of blooming to the surface.

The constitution oi these reaction products is unknown, but it is believed that they contain an appreciable amount of "heterocyclic substances oi saturated quinoline and of indole structure. In the case of aniline and butadiene the reaction is believed to be: 7

+CH:=CH.CH=GH| a mix oontalning v H N CH CH:

2 methyl tetra hydro quinoliuo CHCHa OH| I ethyl 2,3 dihydm indole 2,3 dimethyl 2,3 dihydro indole The following examples are given to illustrate the preparation of the chemicals, and the effectiveness of their use in rubber. The parts are by weight:

' Exmu 1 1,3 dimethyl 1,3 butadiene (21.5 grams), 22 grams p,p" diamino diphenyl methane and a trace ,of iodine as catalyst were autoclaved over night at 200 C. The product was dissolved in benzene, washed with dilute sodium-hydroxide, dried and .the benzene removed by distillation. 25 The residue was freed from unreacte'd p,p diamino diphenyl methane by distilling until the temperature reached 230 C. at 3 mm. (mercury pressure).

, Emu: 2

1,3 dimethyl 1,3 butadiene (16 grams), 30 grams 4 methyl 4 amino diphenylamine and an 0.3 gram of iodine as catalyst were autoclaved over night at 200 C. The reaction product was dissolved in benzene, washed with dilute sodium hydroxide, dried and the benzene removed. The

residue was freed from unreacted 4 methyl 4' amino diphenylamine by distilling to 220 at 5 mms. The product then distilled 220-240 C. at 40 5 mms. (mercury pressure).

EXAMPLE 3 Benzidine (25 grams), 1,3 dimethyl 1,3 butadiene (29 grams) and 0.1 gram iodine were autoclaved over night at 200 .C. The product was dissolved in benzene, washed with dilute caustic. dried and the solvent removed.

' Exmu 4 Butadiene (25 grams), p,p diamino diphenyl methane (40 grams) and 0.1 gram iodine were autoclaved over night at 200 C. The product I was dissolved in benzene, washed with dilute sodium hydroxide and the benzene removed. Unreacted p,p diamino' diphenyl methane was removed by fractionation in vacuum.

Exmu: 5

I Exam ne Aniline (45 grams). 1,3 dimethyl 1,3 butadiene (52 grams) and 1.0 gram iodine were heated under reflux 12 hours. The reaction product was dissolved in benzene. washed with dilute sodium hydroxide, dried and the benzene removed by 4 evaporation. The product distilled 110-110 C.

at 3 mms. (mercury pressure). Only a trace of unreacted aniline was present.

biphenylamine (50:: grams). 1.3 dimethyl 1,3 butadiene (32.8 grams), zinc chloride (5 grams) were dissolved in 100 see. acetic acid and'the solution refluxed 12 hours. Benzene and excess dilute sodium, hydroxide were added and the separated benzene extract washed with water, dried and the benzene removedby evaporation. Theresidue was vacuum fractionated.

Fraction I Boiling range 12o-1so= c. at 3 mms. mercury pressure (unreacted diphenylamine).

Fraction II at... resin. Melting range -85 c. From this resin a small amount of crystalline material, melting point 113-114 C. was isolated.

-EXAIPLI8 N,N diphenyl p-phenylene diamine (33.5 grams), 15.7 grams 1,3 dimethyl 1,3 butadiene, 5 grams zinc chloride and 125 ccs. acetic acid were refluxed i'l hours. The product was isolated as in Example 6; melting range -100 C.

The chemicals are tested in a rubber stock of the composition:

The anti-oxidant to be tested was incorporated in the ratio of one (1.0) part to parts rubber. Cures were made for 10, 20, and 30 minutes at 30 pounds per square inchsteam pressure.

The following data shows the tensile in pounds per square inch and percent elongation at break, before and after ageing 96 hours in oxygen under 300 pounds per square inch pressure.

p p Diamino diplienyl methane- 1,3 dimethyl 1,3 butadiene eactio r :1 product Cure at 1!) pounds steam Control UNAGED rim-m t methyl in the ratio of one (1.0) part to 100 parts rubber. Cures were made for 45, 60 and 75 minutes at 30 Cm 30mm mm mm] 138561.286 1 pounds per square inch steam pressure. Ten- Y 6 siles before and after ageing 96 hours under 300 1,3 butadiene reaction pounds per square inch oxygen are: poduct Aniline-1.3

UNAGED dimeth 11.3

i 10 Cure at 30 pounds steam Control butadLne 2680-736 reaction a p ct zero-07a UNAGED AGED mmmumL m5 45mlnutes 4, j 4,040-003 minutes. Failed ,160050 60 minum" 1W 1W m l w F il d mm 75 minutes 43350-615 i p r AGED Benzidlne-l 3 a dimeth 1' 20 gm Cure at 30 p s e control fi gg ag B 75 minutes p 2, mm

product UNAGED Diphenyl- 2 0.73 2, 40.7 Cure at pounds steam Control afia 3 500-703 2660-676 21mm 4W butadlonc UNAGED 340- 73 15520- 45 30 45 minutes 3,580-690 3,700-690 Failed 2; 160-633 60 m nutes" 3, 780-663 a, 730-003 Failed 1, 75 min tes a, 800-026 a, 300-056 AGED p,p' Diamino I r r g i g 1, me onemmu es. cm at mm butadiene '15 minutes 700-300 2, coo-493 reaction. product UNAGED 40 Diphenyl pdpnenylen; lamina 10 minutes 5* Cure at 30 pounds steam Control dib ngtgyl 1,3

. l1 B. 1836 30 minutes "A. 2, 4M v g t:

pro in AGED 840-573 2', 120-630 UNAGED Failed 1,500-590 I Fafled 680-563 45 minutes asao-eco 3,78lHi86 60minutes----. 3,780-663 3,820-660 75 minutes 3,800-626 asm-oao -Phenylene s sters c Cure at 30 pounds steam Control butad e 2 mm reaction 00 minutes. 2, 190403 Product 75 minutes. 700-300 1,960-453 UNAGED 4 K It is to be understood that the invention may 10 minutes 2,660-730 2, 900-693 be applied to'the preservation of natural rubber 30 minutes fgjg compositions as wellv as artificially-prepared rub- 0 her compositions, including reclaimed rubbers, AGED and latices of such rubber compositions. It is also to be understood that other desired g fgg filling and compounding ingredients may be in- Failed 1 40 550- corporated along with the preservative, for example, in the case oi! rubber there may be incor: porated other accelerators, softeners, etc. Tread master batch The anti-oxidant may be incorporated in any Parts type of rubber composition such as those used, Smoked she 100 for automobile tires and tubes, hose, belting, Carbon black 45 sheet and thread rubber, rubberized fabrics, Zinc oxide 5 molded goods, boots and shoes, etc., where vul- Plne tar--- 3.5 canized in a mold, in open steam, in hot air, or Zinc soap of cocoanut oil fatty acids 3.5 in the cold by the so-called acid process. The Sulfur 3.0 proportion of the anti-oxidant may vary from 'I'he anti-oxidant to'be tested was incorporated about 0.1% to 5%, although either smaller or 7 g v greater proportions may be found useful. It the material to which it is added is a liquid such as rubber cement, the anti-oxidant may be dissolved there in a suitable small proportion. The anti-oxidant may be incorporated into solid substances by milling or mastication and prepared for incorporation into'dispersions or solutions either in powder, paste, or solution form, or applied in such forms for incorporation by diffusion vto the surfaces of vulcanized or unvulcanized rubber goods...

Having thus described our invention, what we u claim and desire to protect by Letters Patent is:

1. A method of preserving organic substances which tend to deteriorate by absorption or oxygen from the air which comprises incorporating therein a product of reaction at a temperature in the range from about 100 C. to about 200 C. in the presence of an acidic catalyst of a monomeric 1,3 butadiene hydrocarbon and a primary aromatic polyamine compound, said amino groups being primary aminogroups, the proportion 01 thesaid butadiene in the reaction mix being in molecular excess compared to the molecular proportion of the amine.

- 2. A method of preserving organic substances which tend to deteriorate by absorption 01' oxygen from the air which comprises incorporating therein aprcduct of reaction at an elevated temperature in the presence of an acidic catalyst of 1,3,dimethyl 1,3,butadiene. 4,4 diamino diphenyl methane, the proportion of said butadiene in the reaction mix being in molecular ex- 4. An organic substance which tends to deteriorate by absorption oi oxygen from the air containing a product of reaction at an elevated temperature in the presence of an acidic catalyst of 1,3,dimethy1 1,3 butadiene, and 4,4'-diamino diphenyl methane, the proportion 01' the said butadiene in'the reaction mix being in molecular excess compared to the molecular proportion of the said amino compound.

'5. A method 01' preserving organic substances which tend to deteriorate by absorption of oxygen from the air which comprises incorporating therein a product of reaction at an elevated temperature in the presence of an'acidic catalyst of a monomeric 1,3 butadiene hydrocarbon and' a diamino diphenyl methane, said amino groupsbeing primary amino groups, the

proportion of the said butadiene in the reaction mix being in molecular excess compared to the molecular proportion of the said amino compound.

6. A method of preserving rubber compositions which comprises incorporating therein a product of reaction at an elevated temperature inthe cess compared to the molecular proportion of the said amino compound.

3. A method of preserving rubber compositions which comprises incorporating therein a product A of reaction at an elevated temperature in the presence of an acidic catalyst 01' 1,3,dimethyl 1,3. butadiene, and 4,4 diamino diphenyl methane, the proportion of the said butadiene in the reaction mix being in molecular excess compared to the molecular proportion oi the said amino compound.

presence of an acidic catalyst of a monomeric 1,3 butadiene hydrocarbon and a. diamino diphenyl methane, the saidamino groups being primary amino groups, the proportion of the said butadiene in the reaction mix being in molecular excess compared to the molecular proportion 01 the said amino compound.

7. A method 01' preserving organic substances which tend to deteriorate by absorption of oxy en from the air which comprises incorporating therein a product of reaction, at an elevated temperature, in the presence of an acidic-catalyst a monomeric 1,3 butadiene hydrocarbon and para-phenylene diamine, the proportion of the said butadiene in the reaction mix being in molecular excess compared to the molecular proportion of the said diamine.

LOUIS H. HOWLAND. PHILIP '1'. PAUL. 

